How to block canvas fingerprinting

One of the threats to privacy is canvas fingerprinting, a way of browser fingerprinting that was created and implemented mainly by AddThis, a web analytics company. However, it is not the only company using it to identify the web browser that you are using, in order to track you and target you with ads while you access different websites. Canvas printing is a script that asks your browser to draw a hidden image and it uses small variations in the way the image is drawn. With this, a unique ID code is generated and it can be used to keep track of you.

Since canvas fingerprinting relies on HTML Canvas API, as well as JavaScript, you can block JavaScript in your browser to disable it. While this is a solution in terms of security, given that a lot of the functionality of the web depends on JavaScript to work, this wouldn’t be a practical option since it can affect your browsing experience. In the same way, it is possible to use Firefox Add-on NoScript to block JavaScript from fingerprinters like AddThis. The problem is that this is a decision that comes with some consequences that need to be considered. It should be noted that NoScript can block JavaScript by default, which can lead to similar issues than the ones experienced when disabling JavaScript. With that being said, if you have advanced technical knowledge, NoScript is the right solution against a variety of online dangers.

You could install the AddThis opt-out cookie in order to prevent targeted advertising by AddThis. However, you would need to rely on AddThis and trust that they will actually not target you with ads. Plus, even installing this, won’t protect you from actually being fingerprinted. This is why a better option would be to use CanvasBlocker. This is also less intrusive than using NoScript and it won’t affect your browsing, which is what blocking JavaScript will do. CanvasBlocker is a Firefox Add-on that blcoks canvas elements on a website and it also gives you more control over the elements that are blocked.

Apart from the default fake readout mode, it is possible to select the way in which CanvasBlocker deals with canvas requests by default. There are different options available. You can block everything, allow only on whitelist, ask for permission, block readout, ask for readout, block only on black list or allow everything. The option to allow canvas in PDFs stands out because like Firefox’s native PDF reader uses canvas to display PDF content. In order to confirm if CanvasBlocker, or any other method to block fingerprinting is working, you can go to the HTML5 Canvas FingerPrinting test page here: Browserleaks.com. You can download the CanvasBlocker Add-on for Firefox from this link: https://addons.mozilla.org/en-US/firefox/addon/canvasblocker/?src=cb-dl-updated and an option for Chrome is available here: https://chrome.google.com/webstore/detail/canvasfingerprintblock/ipmjngkmngdcdpmgmiebdmfbkcecdndc

Using CanvasBlocker is one of the measures that you can use to protect your privacy, but there are other tools that you need to include in your set of solutions to defend yourself from online threats. A VPN is one of the tools that deserves to be included in your daily package of protection to enjoy a safe browsing experience. VPN services applies encryption to your internet connection, so others won’t see what you are doing online. Your activities and conversations are protected and will remain private and it also gives you online freedom as it lets you bypass blocks and restrictions so that you can enjoy more content.